Cascade Control of Ammonia Assimilation
In cellular physiology, metabolism is organized at several levels: the level of intermediary metabolism, the level of protein metabolism (synthesis, modification and degradation), and the level of mRNA metabolism (transcription and decay). At the level of protein metabolism we study cascades of enzymes modifying one another covalently. To this purpose metabolic control theory (MCT) has been extended explicitly to include regulatory cascades. The resulting modular control theory1, which started from the general formalism of Reder2, will be used to analyze the glutamine synthetase regulatory cascade in Escherichia coli. The modular control analysis of this cascade should give insight into how control is distributed over the different hierarchical levels of the cascade, and to quantitate the relative importance of metabolic and genetic regulation of nitrogen assimilation.
KeywordsGlutamine Synthetase Glutamate Dehydrogenase Nitrogen Assimilation RNAse Protection Assay Ammonia Assimilation
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